The moon is the Earth's constant companion, with us every step of the way as we orbit our Sun. But have you ever wondered how it got there, or how the other planets get their multitudes of moons?
The building of planets happens at the same time as the building of stars, in a chaotic and messy process.
A giant cloud of dust and gas collapses and forms a star and through this collapse, a disc of dust and gas forms around the star - very similar to what happens when someone tosses a ball of pizza dough in the air. And from this disc, planets can grow.
The building of planets is a messy process filled with chaos, crashes, and collisions.
Sometimes the building blocks of planets stick together and continue to grow, other times the crashing together of these building blocks can lead to devastating destruction.
It was from this chaos and destruction that our moon was born.
The baby planet that would become the Earth suffered a collision with a Mars sized object called Theia.
From simulations of this crash, it seems that Theia didn't collide head on with the baby Earth, but that it knocked the side of the baby Earth off.
The collision meant that all the bits making up the baby Earth and Theia got mixed together, and for a very short time there was a ring around the Earth, which the moon grew from.
From that chance collision we got something beautiful, our moon.
However, not all moons had such destructive beginnings.
Some planets capture passers-by in their web of gravity and gain moons that way.
This is the case for Mars' two moons - Deimos and Phobos - which are captured asteroids.
This means that as the asteroids were travelling past Mars they got caught in its gravity, becoming bound to Mars.
The giant planets - Jupiter, Saturn, Uranus and Neptune - are a different story altogether.
Giant planets form in much the same way as stars do, from a cloud with a big disc around them, and so their moons can grow from the planet's disc in the same way that the planets grow from the star's disc.
So just like planets growing around stars, moons can grow around the giant planets.
This is especially the case for the larger moons of the giant planets, like Jupiter's moons - Io, Europa, Ganymede and Callisto - or Saturn's largest moon - Titan.
But the smaller ones can be captured as they wander past, just like the case with the moons of Mars.
The same kind of chaotic collisions that led to our Moon can happen when moons are forming around giant planets too, leading to some particularly interesting looking moons such as Saturn's "Death Star" moon Mimas or Uranus' moon Miranda which looks like it was taken apart and awkwardly stuck back together.
So when you look into the sky to appreciate our moon, you can think of the others out there and that there can be beauty when you get through a dark time.
- Eloise Birchall has a Masters of Astronomy and Astrophysics from the Australian National University.